Skip to main content

Full text of "Practical Organic Chemistry"

See other formats


82                PRACTICAL  ORGANIC CHEMISTRY
"now added, drop by drop, from the tap-funnel at the speed at
which the liquid distils, as in the preparation of ether (p. 59)
When all the mixture has been added, the distillate, which con-
tains the ester, and also acetic acid, alcohol, ether, and
sulphurous acid, is shaken in a separating funnel with a strong
solution of sodium carbonate (50 c.c.) until the upper layer of
ethyl acetate ceases to redden blue litmus. The lower layer is
removed as completely as possible, and a strong solution of
calcium chloride (50 grams in 50 c.c. of water) added, and the
shaking repeated. The lower layer of calcium chloride is run
off, and the ethyl acetate carefully decanted from the mouth of
the funnel into a dry distilling flask. A few pieces of solid
calcium chloride are added, and, after standing over night, the
ethyl acetate is distilled from the water-bath with a thermo-
meter in the neck of the flask. The portion distilling below
74° contains ether, that boiling at 74—79° is mainly ethyl
acetate, and is separately collected. Yield, 80 per cent, of
the theory.
C2H5(OH) + H2S04 = C2H5.H.S04 + H,O.
C2H5HSO4 + CH3:CO.OH = CH3.COOC2H6 +"H2SO4.
Properties.—Colourless liquid, with an agreeable fruity smell;
b. p. 77°; sp. gr. 0-9068 at 15°; soluble in about u parts of
water ; miscible in all proportions with alcohol, ether, and acetic
acid,
Reaction.—Weigh out 20 grams of ethyl acetate, and heat in a
round flask with three times its volume of aqueous potash
(iKOH : 3H2O) with upright condenser over wire-gauze*. Add
a small piece of porous pot to prevent bumping. After an hour
or so the upper layer of ethyl acetate will have disappeared. Distil
the product with a thermometer.until the temperature reaches
100°. Add solid potassium carbonate to Aie distillate until no
more dissolves. Separate the top layer of alcohol and dehydrate "
over fresh potassium carbonate or quicklime. Distil with a
thermometer and weigh the distillate. Neutralise the alkaline
liquid, from which the alcohol was fust distilled, with dilute sul-
phuric acid, and evaporate to dryness on the water-bath. Break
up the solid resjdue, and distil with concentrated sulphuric acid
(20 c.c.) until the thermometer marks 130°. Redistil and collect